Working for salary should not imply working 'free' hours. Being paid salary means you get paid to do a job, not just to be present. Now there are *many* companies that abuse the concept of salary pay to get free over time, but that does not mean all of them do it nor that you should put up with it. I work for a company that at times makes large demands of my time with occasional trips out of town (effectively all of my time is eaten). But on the same token, when the big push is over, no one cares if you show up a bit late or leave a bit early (yes it does happen). I am really lucky in that during (youth) baseball season, my work overlooks all the time I am present, but dealing with baseball matters, parents, coaches, umpires, scheduling, lineups (I coach in addition to working on the board) and various board matters. Not to mention the times I leave very early to prepare for and coach or umpire games.
So long as I delver on time and am around so proper communication can occur, no one complains. If I miss my deadlines, then I either need to spend more time per day to get the job done or need to give better estimates and set reasonable expectations. My schedule is not much less flexible than 1099 development work have done full time in the past. Customer needs dictated much of that work occurred at specific times and I still had schedules and expectations to make. Not to mention that you generally do not work 1099 jobs for 'as long as it takes' (yes some contracts are open-ended). Customers expect much like my current job, that I can gather the necessary information to make accurate time estimates and thus make reliable cost estimates which are negotiated up front. I then give a price for the *job*. Chances are if you underestimate the time it takes you to write a contact application, that you 'eat' the extra hours. If you are smart, you do not allow much in the way change orders without additional payment and time being added. If you have open ended development work, then you either are very good at negotiation or have a very dumb customer (I have seen this too, and happy to comply of they are that stupid).
Working 1099 is much like working mini salary jobs. You get to negotiate your salary more often depending on the length and number of 'jobs' or contracts.
Now you may be working a support type contract in which you get paid for number of 'base' hours with an open-ended agreement for extra paid hours as-needed, but then you have to live with the times when you are not needed and get the minimum hour payments. You DO make them pay for a base amount of hours even if not used, right? That's how they get to pay you $100/hr instead of $120 those months they needed you for five times the base number of hours. Yes you are not working 'free' hours but then you may not get many hours at all. Now if you are smart, you have many of these contacts and total of all the base hours is at least the needed income to get by comfortably but not so many hours that you have no free time, otherwise, what is the point, right?